<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .bolls {
            width: 200px;
            height: 400px;
            padding-top: 100px;
            margin: 100px auto 0;

            filter: url(#blob);

            /* background: #fff; 
              filter: contrast(10); */
        }

        .boll {
            margin: auto;
            width: 100px;
            height: 100px;
            border-radius: 50%;
            background: #28c840;
            /* filter: blur(10px); */
        }

        .boll:last-child {
            margin-top: -20px;
        }
    </style>
</head>

<body>
    <div class="bolls">
        <div class="boll"></div>
        <div class="boll"></div>
    </div>

    <svg style="display:none">
        <defs>
            <filter id="blob">
                <feGaussianBlur in="SourGraphic" stdDeviation="10" result="blur"></feGaussianBlur>
                <feColorMatrix in="blur" mode="matrix" values="
                1 0 0 0 0
                0 1 0 0 0
                0 0 1 0 0 
                0 0 0 20 -10"></feColorMatrix>
            </filter>
        </defs>
    </svg>
</body>

</html>